someone who makes sense.

but,,no,,no we aint tradin !!

hard tires and a soft foot=free mileage

oh, on tires; i now have 285,had 265
if i get less mpg going from 265 to 285, would i beat 265 mileage with 255 or 245??
even if i went back to 265 it costs me?$600?
lots of gas,cant win

 

Well Doc, if going larger (like to 315's) robs power and acceleration, imagine what going to a super small 14" 215 would do for ya! Bwahhh.....hahahahahahaha

 

actually im dead serious. i wonder if 265,(20mpg), is the magic sweet spot for the h3 or , since 285 reduces mpg,might 255 increase it.we only see the results of bigger tires and its negative for mpg.smaller might be better. but i would not want my old pinto 185 75 14,,,no not really xxx xxxx!

 

As far as mileage goes, I bet you're right on with the 265's being the sweet-spot.

 

If you go to small, you will lose mileage on the interstate because you will then be running higher RPMs to go the speed limit. Thus, reducing your gas mileage

 

YEAH but the reverse dont work,,,go up to285 run lower rpm ,sounds logical,,,but it dont work!!! sorry

actually smaller,more power,ezer to push.it balances out at some point.
weight,the brick shape,tire air pressure.
one thing we know,265 beats 285. so its 255?,or,275?
best guess IS 265,what gm put on to start,huh?

 

Aside from the vortex thing, I've heard the little magnets you put on the fuel line work great too. I think Doc Olds recommends those highly . Other than the new intake, exhaust and pcm tune, I think the e-fan is the way to go. Probably my next and last mod (I think anyway) but that'll probably be an end of summer thing. Of course along with these mods I'm adding weight with bigger tires and a BG so if anything if I'm lucky if the MPG mods will offset my other add ons.

Ben

 

Yall are getting the width of the tire (e.g. 285, 265, etc) confused with the overall diameter of the tire. A 285/75R16 will be about the same overall diameter of a 265/75R16. The 265 would theoretically get better gas mileage because it is more narrow and has a smaller contact patch on the road (less friction). At some point you could get too narrow and adversely affect handling and braking performance.

A 285/70R16 will be a smaller overall diameter than the 285/75R16.

 

lots of tires,lots of charts.
285, apx 33 in
265, apx 31.5
255 if u find comparable, apx30

so bigger numbers in same group,bigger than smaller numbers,,,
im just curious what the fine tune spot is,not that im gonna spend 800 to find out

 

You statement is innacurate for many reasons. I'll stick to the easy one and with GM trucks. You made a blanket assumption that throttle bodies on a particular engine application are the restriction point in the entire intake to the combustion chamber. Simple example would be the I5 motors that use a TB daimeter capable of feeding much larger CI motors than necessary for the 3.5s and 3.7s. In other words, when you increase flow to the entry of the TB, you do in fact increase flow to the combustion chamber starting as low as 2200 RPMs increasing exponentially as RPMs increase. The I5 TBs can flow more than what the OEM intake system restrictions allow thus negating your assumption.

This is why a Dyno can measure an increase in HP and TQ when a performance intake is added without any other change. Some vehicles respond fantasically to the addition to an intake, others to a lesser extent.

If you add an intake, PCM tune, and Efan conversion your MPG will go up with every addition without any other changes. How much depends upon how you drive. In all the late model trucks we have tested, I cannot say that you can measure anything by adding a Cat Back Exhaust but tuned sound. The old adage: more air in, more air out cannot hurt anything and does have some truth about it.

BTW, performance modding for 99% of people is not about a cost analysis of how long a certain mod will take to pay for itself in fuel savings, it is about making your truck, "your truck", increasing performance and at the same time, maybe picking up some extra miles every tank of fuel.